The invention relates to an arrangement for securing a switch control shaft to a switch pipe shaft, where the control shaft is mounted partly in the switch pipe shaft and tightened to the switch pipe shaft by a screw.
The invention relates to switchboard cabinets which include a control handle arranged in the cabinet door or the like for controlling a switch included in the switchboard cabinet from outside the cabinet and in which a switch control shaft is arranged between the control handle and the switch for transmitting the rotational motion directed at the control handle to the switch and for turning the switch from one operating position to another.
The switch is typically mounted on a baseboard included in the cabinet and the control handle of the switch is installed in the cabinet door at the site of the control mechanism. For the switch control handle to be placeable at a distance from the actual switch, i.e. in the cabinet door so as to enable controlling the switch by the control handle arranged in the door, the control shaft of the above-mentioned switch is arranged between the switch and the control handle.
The switch control shaft is usually a bar with a square cross section, whose one end goes inside the pipe shaft provided in the switch, into a space with a square cross-section, and whose other end extends to a corresponding opening with a square cross section in the control handle installed in the door. When the switch is turned, the control handle pivots around its longitudinal axis, whereby the switch turns into another operating position.
In the installation stage, the control shaft is cut roughly to the correct length and adjusted to its exact length by testing, and finally the control shaft is secured, i.e. locked, to the pipe shaft. The length of the control shaft depends on the distance between the switch and the cabinet door, i.e. the opening for the control handle in the door. Since the switch control handle is installed in the door of the cabinet, the control shaft has to remain secured to the switch when the door is opened. The control shaft should also stay in the same position during the whole time the door is open so as to facilitate the closing of the door and the placing of the control shaft in the opening of the control handle (inside the door).
The control shaft is conventionally secured, i.e. locked, to the pipe shaft by means of screw fastening. In a prior art solution, on the side of the pipe shaft, there is a through threaded hole, through which a locking screw locks the control shaft to the pipe shaft of the switch. The locking screw presses the control shaft against the pipe shaft so that the control shaft locks, i.e. tightens fast between the locking screw and the inner surface of the pipe shaft. The middle axis of the threaded hole and the middle/longitudinal axis of the switch pipe shaft are thus substantially transverse to each other in this prior art solution.
A problem associated with the arrangement described above is that since the adjustment of the control shaft and its locking into position with respect to the pipe shaft are usually performed in a fully-equipped cabinet, it is difficult to access the screw for tightening from the side of the pipe shaft.